Fluid pressure actuated clamp



1970 A. L. TROUTNER 3,490,759

FLUID PRESSURE ACTUATED CLAMP Filed Jan. 10, 1968 INVENTOR. ARTHUR LTROUTNER BY ATTY.

United States Patent US. Cl. 269-35 8 Claims ABSTRACT OF THE DISCLOSURE A fluid-pressure-actuated clamp comprises a pair of spaced frame members positioned on opposite sides of a plurality of objects to be clamped together. A pair of bearing pads mounted on the frame members bear against the opposite side faces of the objects. A pair of clamp bars mounted on the frame members bear against the opposite end adges of the objects. Fluid operated piston means mounted in one of the bearing pads supports the pad for floating movement on the frame member. Cooperating cam and cam follower means are mounted on the clamp bars and frame members. Upon actuation of the piston means, the pads and clamp bars are drawn toward each other, thereby simultaneously applying clamping pressure to all sides of the objects.

This invention relates to fiuid-pressure-actuated clamps. It pertains particularly to fluid-pressure-actuated lamination clamps employed in the manufacture .of laminated beams by gluing together a plurality of boards, face to face.

In the manufacture of glued, laminated beams the glue is spread on the face surfaces of individual boards which then are placed face to face in a press. Wrench-operated screw jacks are applied to the assembly at spaced intervals to maintain the necessary clamping pressure while the glue sets. This conventional procedure has several important disadvantages.

First, it is essentially a hand operation and requires a great deal of labor.

Second, as the boards are pressed they tend to slip out of line in a direction perpendicular to the line of pressure. This requires hammering them back into line with large hammers and blocks.

Third, the glue lines near the outer edges of the beam are pressured unevenly due to the point pressuring of the individual clamps. This produces non-uniform bonding along the length of the beam.

Fourth it is difficult to apply predictable pressure on any or all of the glue lines of the individual laminations because of the many variables involved, i.e. wrench torque calibration, the condition of. the threads and nuts on the screw jacks, and the condition of lubrication of the screw -acks.

1 It is the general purpose of the present invention to provide a fluid-pressure-actuated clamp which overcomes the foregoing problems.

In the drawings:

FIG. 1 is a foreshortened view in side elevation of the clamp, partly in section;

FIG. 2 is a fragmentary, detail plan view looking in the direction of the arrows of line 22 of FIG. 1;

FIG. 3 is a fragmentary, perspective view of a clamp bar mounting employed in the clamp; and

FIG. 4 is a fragmentary, plan view of a laminated beam in the process of manufacture, the beam having applied thereto a plurality of the hereindescribed clamps.

In its broadest aspect the clamp of my invention comprises a pair of spaced frame members positioned on op- 3,490,759 Patented Jan. 20, 1970 ice posite sides of a plurality .of objects to be clamped together. A pair of bearing pads mounted on the frame members bear against the opposite side faces of the objects. A pair of clamp bars mounted on the frame members bear against the opposite end adges of the objects. Fluid operated piston means mounted in one of the bearing pads supports the pad for floating movement on the frame member. Cooperating cam and cam follower means are mounted on the clamp bars and frame members.

In the operation of the clamp, extension of the piston presses the bearing pads against the opposite sides of the objects. At the same time, through the operation of the cam, the clamp bars are forced against the tops and hottoms .of the objects. Thus clamping pressure is applied to all sides of the objects at the same time.

Considering the foregoing in greater detail and with particular reference to the drawings:

As seen in FIGS. 1 and 4 the clamp of the invention is applied to clamping together a plurality of boards 10 to the faces of which glue has been applied, preliminary to gluing them together in the manufacture .of a laminated beam. The clamp is supported on a base 12. It includes a pair of short frame members or posts 14, 16 arranged one on each side of the boards and placed vertically in the normal use position of the clamp.

Post 14 comprises a pair of side plates 18, 20 the ends of which are angled outwardly, and a pair of cross plates 22-24 welded centrally to the side plates. A foot 26 is welded between the lower ends of the side plates and is supported on base 12.

The construction of post 16 is similar. It comprises a pair of side plates 29, 30 having terminal portions angled outwardly and interconnected by a pair of cross plates 32,34. A foot 36 is welded to the lower ends of the side plates and slides on support 12.

The construction of the posts thus is such that there is provided in each a central box section of considerable strength, and terminal sections having both aligned slots and outwardly divergent camming edge surfaces 18a, 18b, 20a, 20b, 28a, 28b and 30a, 30b.

Post 14 in unison with the corresponding posts of companion clamp units supports an elongated bearing pad 40 provided with spaced access openings 42. This important member of the assembly has for its function exerting hearing pressure against one of the side faces of the board assembly. For strength and rigidity it preferably comprises a box beam of the indicated construction. It is fastened to posts 14 by means of bolts 44 which are tightened down through access opening 42.

Post 16, in unison with the corresponding posts of companion clamp units, supports a cooperating bearing pad 50. Bearing pad 50 is recessed and has for its function exerting clamping pressure continuously against the opposite side face of the assembly of boards. For rigidity and strength it, too, is of a substantial box beam construction. It is provided at spaced intervals with openings 52.

Coil springs 53 interconnect the outer end wall of bearing pad 50 and side plates 28 of post 16, normally urging the bearing pad outwardly.

Bearing pad 50 houses a piston element 54 by means of which the clamping force is applied to the assembly. This element also advantageously may comprise a box beam, but of smaller cross section, so that it nests within bearing pad 50. Attached to its opposite sides are a pair of blocks 56 which serve three important functions:

First, they center the piston within the bearing pad.

Second, they act as slides during the reciprocating movement of the piston.

Third, they serve as stops or abutments against which bears the fluid pressure member by means of which the piston is actuated.

Piston 54 is provided -with a extension 58 serving the function of a short piston rod. This member may be formed integrally with the piston, or, preferably, as a spacer element. It extends through opening 52 in bearing pad 50 and bears against cross plate 32 of post 16 which accordingly serves as a cross head for the piston assembly.

Bearing pad 50 and the piston assembly which it houses are supported in a floating condition on a plurality of bolts 60 penetrating both post 16 and piston rod 58 and threaded into the side wall of piston 54.

The actuating means for the piston assembly is illustrated in FIG. 1. Conceivably it could comprise a fluid introduced in the reservoir present behind blocks 56. For practical reasons, however, it is preferred to locate in this reservoir an expandable tube 62 made of rubber or other resiliently expandable material. It extends the length of the bearing pad, is closed at both ends, and is supplied with air or other fluid under pressure by means of conduit 64 which is mounted in hollow piston member 54.

Introduction of pressurized fluid into tube 62 advances piston 54 causing piston rod 58 to bear against post 16 and, as a result, causing floating bearing pad 50 to bear against one of the side faces of the assembly of boards 10. Means are provided for transferring this drive not only to the cooperating bearing pad 40, which bears against the opposite side face of the assembly, but to appropriately disposed clamp bars which at spaced intervals bear against the opposed edges of the board assembly. The means for accomplishing this purpose are illustrated in FIGS. 1, 2 and 3.

An upper clamp bar 70 is received in the aligned slots formed by the outwardly angled upper extensions of the side plates of posts 14, 16, which accordingly overlap the clamp bar. The clamp bar is formed at one end with a plurality of spaced openings 72 journaling the shaft 74 of a pair of detachable rollers 76 which cooperate with a pair of non-detachable rollers 76 mounted on the other end of the clamp bar. All of the rollers act as cam followers, tracking on cam surfaces 181:, 20a, 28a, 30a during the operation of the clamp. Although rollers are a preferred type of cam follower to be applied for this purpose, it will be apparent that wedge or other fixed surfaces may be aflixed to the ends of clamp bar 70 to serve the same purpose.

A second or lower clamp bar 80 cooperates with upper clamp bar 70. It, too, is provided on one end with a plurality of spaced openings 82 into a selected one of which is journaled the shaft 84 of detachable cam rollers 86. These cooperate with a pair of non-detachable cam rollers 86 rotatably mounted on the other end of clamp bar 80.

Clamp bar 80, with rollers 86 removed, is insertable in the slot provided by the outwardly divergent terminal portions of the side plates of posts 14, 16 placing rollers 86 in contact with cam surfaces 18b, 20b, 28b, and 30b.

In the use of the clamp, a suflicient number of clamp units are provided to accommodate the components of the laminated beam or other product to be fabricated. These are arranged at suitable intervals so that clamping pressure may be applied to the objects in the desired locations.

Then, in each unit, one of wheel assemblies 86 of lower clamp bar 80 is removed and the clamp bar inserted in the lower slots of posts 14, 16. The wheel assembly is mounted in the appropriate one of bearing openings 82. The particular opening will be determined by the width of the assembly to be pressed and the stroke of piston 54.

Next, with bag 62 deflated and bearing pad 50 moved to its expanded position by the action of springs 53, boards having glue applied to their interfaces are laid edgewise on lower clamp bar 80. The wheel assembly of 76 of upper clamp bar 70 then is adjusted in a bearing opening 72 corresponding to the one used in the lower clamp bar to mount the wheels. The clamp bar is slipped in the upper slots of posts 14, 16.

Upon filling tube 62 with compressed air or other fluid under pressure, piston 54 and piston rod 58 are moved outwardly into bearing engagement with the central portion of post 16. Since bearing pad 50 floats, it is urged inwardly into bearing engagement against the opposed side face of board assembly 10.

At the same time, movement of post 16 outwardly takes up the slack between clamp bars 70, 80. Continued movement of post 16 causes cam rollers 76, 86 to track on the adjacent cam surfaces of the post extensions. This draws the clamp bars inwardly, toward each other, and in clamping engagement with the edge surfaces of the boards.

Clamping pressure is maintained until the glue sets. The fluid under pressure then is drained from tube 62 whereupon springs 53 draw bearing pad 50 to its retracted position. Clamp bars 70, become loose and clamp 70 may be removed to allow unloading of the cured, laminated product.

The objectives of the invention thus are achieved. Clamping pressure is applied uniformly to all four sides of the object to be pressed. Slipping of the objects out of line is prevented. The predetermined pressure is maintained at all times. A minimum of labor is required. Also, the speed with which the clamp may be applied is accelerated materially.

It is to be tmderstood that the form of my invention herein shown and described is'to be taken as an illustrative example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, 1 claim:

1. A fluid-pressure-actuated clamp comprising:

(a) a first frame member adapted to lie on one side and a second frame member adapted to lie on the other side of a plurality of objects to be clamped together,

(b) a first bearing pad secured to one of the frame members and arranged for hearing against one side of the objects,

(0) a floating, recessed second bearing pad positioned adjacent the other frame member and arranged for bearing against the other side of the objects,

(d) piston means mounted for sliding movement within the second bearing pad,

(e) piston rod means interconnecting the piston means and the second frame member,

(f) fluid pressure applying means located in the second bearing pad behind the piston means for moving the piston means and the second frame member in a direction away from the first frame member.

(g) a first clamp bar adapted to underlie and a second clamp bar adapted to overlie the objects, overlapping the frame members and (h) cooperating cam and cam follower means mounted respectively on the overlapped portions of the clamp bars and frame members and operative upon actuation of the piston means to move the first and second clamp bars toward each other, thereby simultaneously applying clamping pressure to all sides of the objects.

2. The fluid-pressure-actuated clamp of claim 1 Wherein the ends of the frame members are slotted to receive the clamp bars with their ends angled divergently away from each other to provide inclined cam edge surfaces, and wherein the cam follower means are mounted on the cam bars in camming engagement with the cam edge surfaces.

3. The fluid-pressure-actuated clamp of claim 2 wherein the cam follower means comprise rollers rotatably mounted on the clamp bars.

4. The fluid-pressure-actuated clamp of claim 2 wherein the opposite ends of the clamp bars are provided with a plurality of linearly spaced transverse openings and wherein the cam follower means comprise rollers mounted on shafts journaled in selected ones of the openings.

5. The fiuid-pressure-actuated clamp of claim 1 wherein the second bearing pad comprises a hollow beam having an opening opposite the second frame member, wherein the piston means comprises a beam of smaller cross section nesting within the hollow beam, and wherein the piston rod means comprises an extension of the second beam projecting outwardly through the opening in bearing engagement against the second frame member.

6. The fluid-pressure-actuated clamp of claim 1 wherein the second bearing pad comprises a hollow beam having an opening opposite the second frame member, wherein the piston means comprises a beam of smaller cross section nesting within the hollow beam, and wherein the piston rod means comprises an extension of the second beam projecting outwardly through the opening in bearing engagement against the second frame member, and bolt means interconnecting the piston and the second frame member for supporting the piston on the second frame member.

7. The fluid-pressure-actuated clamp of claim 1 wherein the second bearing pad comprises a hollow beam having an opening opposite the second frame member,

wherein the piston means comprises a beam of smaller cross section nesting within the hollow beam, and wherein the piston rod means comprises an extension of the second beam projecting outwardly through the opening in bearing engagement against the second frame member, and resilient means interconnecting the second bearing pad and the second frame member for maintaining the piston means normally in its retracted position.

8. The fluid-pressure-actauted clamp of claim 1 wherein the fluid pressure applying means comprises a sealed, expandable tube provided with connecting means for connecting it to a source of fluid under pressure.

References Cited UNITED STATES PATENTS 1,312,615 8/1919 Cooper 26922 XR 2,560,902 7/1951 Smith 269-22 FOREIGN PATENTS 939,983 1948 France.

ROBERT C. RIORDON, Primary Examiner D. D. EVENSON, Assistant Examiner 

